erofs-utils: fix build error when `-Waddress-of-temporary` is on

Actually, it's false positive and only used for build assertion.

Reported-by: Kelvin Zhang <zhangkelvin@google.com>
Signed-off-by: Gao Xiang <xiang@kernel.org>
Link: https://lore.kernel.org/r/20230920200314.9193-1-hsiangkao@aol.com

diff --git a/include/erofs_fs.h b/include/erofs_fs.h
index bdc946ac0c783123a3262028142376a9d5ad0e94..eba6c26d0253dd5093a9d6a950f346b3947f9f63 100644 (file)
--- a/include/erofs_fs.h
+++ b/include/erofs_fs.h
@@ -440,10 +440,12 @@ struct z_erofs_lcluster_index {
 /* check the EROFS on-disk layout strictly at compile time */
 static inline void erofs_check_ondisk_layout_definitions(void)
 {
-       const __le64 fmh __maybe_unused =
-               *(__le64 *)&(struct z_erofs_map_header) {
-                       .h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT
-               };
+       const union {
+               struct z_erofs_map_header h;
+               __le64 v;
+       } fmh __maybe_unused = {
+               .h.h_clusterbits = 1 << Z_EROFS_FRAGMENT_INODE_BIT,
+       };
 
        BUILD_BUG_ON(sizeof(struct erofs_super_block) != 128);
        BUILD_BUG_ON(sizeof(struct erofs_inode_compact) != 32);
@@ -463,8 +465,8 @@ static inline void erofs_check_ondisk_layout_definitions(void)
        BUILD_BUG_ON(BIT(Z_EROFS_LI_LCLUSTER_TYPE_BITS) <
                     Z_EROFS_LCLUSTER_TYPE_MAX - 1);
        /* exclude old compiler versions like gcc 7.5.0 */
-       BUILD_BUG_ON(__builtin_constant_p(fmh) ?
-                    fmh != cpu_to_le64(1ULL << 63) : 0);
+       BUILD_BUG_ON(__builtin_constant_p(fmh.v) ?
+                    fmh.v != cpu_to_le64(1ULL << 63) : 0);
 }
 
 #endif